Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
from collections import deque

H,W=map(int,input().split())
s=[input() for _ in range(H)]

q= deque([[0,0]])
f=[[-1 for j in range(W)]for i in range(H)]
f[0][0] = 0
dxy=[[1,0],[-1,0],[0,1],[0,-1]]

while q:
    x,y =q.popleft() 
    for dx,dy in dxy:
        dx += x
        dy += y
        if dx >=0 and dy >= 0 and dx<H and dy<W:
            if s[dx][dy] == "." and f[dx][dy]==-1:
                f[dx][dy] = f[x][y]+1
                q.append([dx,dy])

res = 0
for i in range(H):
    res += s[i].count(".")
if f[H-1][W-1]==-1:
    print(-1)
else:
    print(res - f[H-1][W-1] -1)